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List of filename extensions and languages

If a source file name ends in one of the following extensions, then GDB
infers that its language is the one indicated.
     C source file

C++ source file

     Objective-C source file
     Fortran source file
     Modula-2 source file
     Assembler source file.  This actually behaves almost like C, but
     GDB does not skip over function prologues when stepping.
   In addition, you may set the language associated with a filename
extension.  *Note Displaying the language: Show.